One of the pillars of the Fast and the Furious universe’s lore—and if you have not been keeping up with the franchise, you might be surprised at how much lore it’s accumulated—is the existence of “NOS,” short for nitrous oxide, which Vin Diesel’s Dominic Toretto and his ever-expanding crew use to give themselves an extra boost of speed just when they need it most. They’re racing along, trailing their opponent by inches, unable to make up the distance as the finish line approaches, when they’ll hit a button, inject some NOS into their fuel stream, and cruise to a narrow but satisfying win.

The Fast and the Furious series hit the NOS button with 2011’s Fast Five, which transformed it from a string of movies about people who race cars into a globetrotting action franchise in which cars are occasionally—and increasingly less plausibly—involved. Bloomberg neatly documented as much in a statistical breakdown which showed the time spent on actual car racing dwindling to a measly 33 seconds in 2015’s Furious 7. The Fate of the Furious, the eighth movie in the series (yes, it really is spelled Fate instead of F8, but that is the film’s lone gesture of restraint), reverses that trend, opening with a lengthy race through the streets of Havana slickly directed by franchise newcomer F. Gary Gray (helming his first film since Straight Outta Compton).

The sequence, shot in earthy, saturated colors, gives Gray a chance to train his camera on several voluptuous, barely covered rears, a necessity for a series that is to ass shots what water lilies were to Monet. But it also serves as a kind of subliminal reassurance to fans unsettled by the loss of Fast/Furious mainstay Paul Walker, who was killed in a car crash midway through the filming of Furious 7, that Walker’s death won’t cut the series off from its roots.

That reassurance lasts about five minutes, until Charlize Theron’s evil hacker Cipher crashes Dom’s Cuban honeymoon and blackmails him into turning against his comrades, a team that includes his wife Letty (Michelle Rodriguez), longtime running buddies Roman (Tyrese Gibson) and Tej (Chris “Ludacris” Bridges), and newish additions Ramsey (Nathalie Emmanuel) and Hobbs (Dwayne Johnson). The idea of Dom’s crew as a surrogate family has been hammered home with comical frequency—don’t do a game where you drink every time Diesel says the word family unless you have some activated charcoal near at hand—especially as the movies have swelled and strayed farther from reality. Their clunky sentimentality is what keeps the Furious movies grounded even as the need to craft bigger and more outlandish stunts has made them increasingly hostile to the nettlesome laws of physics.

There’s a certain logic to the idea that Fate should put that idea of family to the ultimate test, forcing its most vocal proponent to betray his own oft-stated ideal. (The movie holds back for a while exactly what leverage Cipher has over Dom, but suffice it to say that it dovetails neatly with the same theme.) But separating Dom from the group also means the narrative has to run in several different directions at once, and there isn’t enough story to keep it going. Fate pares back the sprawling cast of its predecessors somewhat, but it also adds Scott Eastwood as a rule-following adjunct to Kurt Russell’s black-ops taskmaster and contrives to have Jason Statham’s Deckard, the previous movie’s main antagonist, jump the fence and start working with, if not for, the good guys.

Deckard’s shift of allegiances goes down especially rough for those who view the Furious movies as more than collection of action set pieces separated by filler scenes just long enough to let them catch up on their missed texts. (We’ll get to the set pieces shortly, but if the highlight reel is all you’re after, you won’t leave disappointed.) It was revealed at the end of the sixth movie that Deckard was responsible for the death of the crew’s beloved Han (Sung Kang), a character so popular that the series effectively turned three movies into prequels to 2006’s Tokyo Drift to bring him back from the dead.

The Fate of the Furious mumbles a few words about how Deckard and Hobbs are the only two people in the world who’ve ever managed to track Dom down and so they’re the best chance for finding him now, but the integration of a cold-blooded murderer into the crew’s ranks is accomplished without so much as a token demonstration that Deckard is inclined to change his spots. More Jason Statham in studio blockbusters is a welcome development: There’s a sequence near the end of Fate that involves Statham killing his way through a crowd of henchmen while toting an infant car seat that’s like the Crank 3 we’re unlikely to get. But in Fate, it comes at the cost of dynamiting whatever shred of credibility the series has left.

One can make the colorable claim that credibility matters little in a movie in which Vin Diesel drives a flaming car backwards through the middle of a city and an orange Lamborghini is chased across a Russian ice floe by a submarine. If the question with which you approach The Fate of the Furious is “Does it feature a sequence in which self-driving cars speed through the windows of Manhattan skyscrapers and smash onto the streets below like very expensive rain?” then yes, you are likely to leave fulfilled. But even within the world of the Furious movies, where vintage American muscle cars are sturdier than tanks and faster than jet planes, some of Fate’s stunts are difficult to embrace. (The only way to explain how Dom escapes after his car is punctured by five separate grappling hooks is that a wizard did it.)

It’s worst in the sequence where Hobbs and Deckard fight their way out of prison, with Johnson throwing bodies dozens of feet in the air and Statham springing off walls as if he’s been bitten by a radioactive spider. The moments where the two of them butt heads are some of Fate’s best; despite their relatively late arrival to the franchise, they’re the best at nailing the right balance of musclebound bluster and tongue-in-cheek self-awareness. But they feel like scenes from a different movie—or really, from any number of movies.

The Furious series has been headed in the direction of Bondsville for some time, and with the arrival of Theron’s Cipher, swathed in ratty blond hair extensions and intent on seizing control of the world’s nuclear arsenals, it pulls comfortably into a spot out front. But Theron seems strangely reluctant to have fun with the part, and given her athletic turns in Mad Max: Fury Road and the forthcoming Atomic Blonde, there’s something perverse about sticking her in a role where the only thing she does furiously is tap at a keyboard.

The series has had an implausible, possibly unprecedented arc, hitting its stride with the fourth in the series and keeping its core cast together even as the movie’s global box-office takes have skyrocketed. (It helps that none of the original stars have shown much of an ability to draw crowds on their own. Vin Diesel is to muscle cars what Esther Williams was to swimming pools.) But with The Fate of the Furious, it feels like the movies have gotten as big as they can get, and the gleeful absurdity that drove them is losing ground to the specter of obligation. The NOS is starting to wear off, and with two more movies in the works, the finish line is nowhere in sight.

Vin Diesel in Fate of the Furious. Universal Pictures

'Fate of the Furious' settles for cruise control

Paul Walker's untimely death forced the "Fast & Furious" franchise into a rare moment of sobriety, an interlude that hits the brakes with "The Fate of the Furious." Yet even more free-spirited mayhem doesn't rev up the eighth installment in this hugely lucrative series, specializing in fast cars and artfully blowing stuff up.

At this point, shuffling alliances and adding a few big-name actors (principally Charlize Theron, here as a Bond-esque cyber-villain known as Cipher) is about all that can be done to distinguish one outing from the next, which doesn't prevent the movie from feeling mechanical, and -- at well over two hours -- a little bloated.

With nuclear weapons in the mix, nobody can accuse this latest adventure of playing for small stakes. Still, "Fate of the Furious" (which eschews designating its sequel status numerically, other than its Twitter hashtag) only sporadically sparks to life, with the best recurring bit involving the macho banter between Dwayne Johnson and Jason Statham's characters, which eventually prompts even these tough guys to burst out laughing.

The plot, such as it is, proves almost incidental. After an opening sequence set in Cuba that mostly squanders that locale, the gruff automaton Dom (Vin Diesel) encounters Cipher, who finds a way to coerce him into assisting her.

Having Dom go "rogue," as federal agent Luke Hobbs (Johnson) puts it, throws his team into a tizzy, forcing them into an uneasy alliance with the aforementioned Deckard Shaw (Statham). That leads to a globetrotting quest to thwart Cipher's plans.

Even by the standards of the genre, the storytelling is occasionally clunky -- in one instance, awkwardly transitioning almost mid-scene into an action sequence in Berlin, as if director F. Gary Gray suddenly decided that it was time to speed away from pesky dialogue and exposition, pronto.

Theron, meanwhile, proves a pretty stock villain, saddled with dialogue rote enough that it would be fair to just assume her aims are nefarious and get on with it.

Inevitably, the main draw remains the elaborately mounted driving pieces. But even those have a certain off-the-assembly-line quality, as well as a need to keep ratcheting up the military hardware. By the time the heroes are chasing a nuclear submarine, the excitement factor is on fairly thin ice.

It's equally true that these movies are almost wholly review-proof, making puny critics pretty well irrelevant. Die-hard fans will likely feel they got their money's worth, and pocketing boatloads (or U-boat loads) of money is a virtual certainty.

Although these movies have become a major franchise with more sequels already lined up, there's room to maneuver even within the confines of a formula. "Fate of the Furious," by contrast, appears content to coast along on cruise control.

Insiders: Vin Diesel Killed a ‘Fate of the Furious’ Scene With The Rock and Jason Statham (Exclusive)

It looks like the feud between Vin Diesel and Dwayne "The Rock" Johnson isn't over: Diesel, a producer of "The Fate of the Furious," killed plans for a scene at the very end of the mega-sequel that would have featured his co-stars, Johnson and Jason Statham, insiders exclusively told TheWrap.

The scene -- described as a short "tag" to the story -- featured The Rock's character, Luke Hobbs, and Statham's character, Deckard, who develop a rapport over the course of the film.

"They had early screenings where Johnson and Statham popped so much on-screen together that they were looking at doing a spinoff," one insider said.

The tag would have kept their banter going -- but Diesel intervened, according to people close to the production.

Producer Neal Moritz had the tag filmed without Diesel's knowledge, the insiders said. When executive producer Samantha Vincent, Diesel's sister, learned of the scene and told Diesel, he became enraged, according to the insiders.

They said Diesel then called the film's studio, NBC Universal, to explosively air his grievances. The studio had all the theatrical prints recalled and cut the scene, the insiders said.

Another insider put it more diplomatically, saying that the sequence was initially shot as bonus content for home entertainment release. When studio executives and filmmakers reviewed the sequence that included Johnson and Statham, they "loved it," but ultimately decided not to include it in the theatrical release because "the sequence would make for a better opportunity somewhere else," the insider said.

Representatives for Moritz, Diesel and Johnson did not respond to requests for comment. Representatives for the studio and Statham declined to comment on the scene.

Last year, during production of the film, Johnson expressed his frustrations with male co-stars he didn't identify. "Some conduct themselves as stand-up men and true professionals, while others don't," he wrote on Instagram. "The ones that don't are too chicken s-- to do anything about it anyway. Candy a----. When you watch this movie next April and it seems like I'm not acting in some of these scenes and my blood is legit boiling -- you're right."

TMZ reported at the time that Diesel was the co-star Johnson was calling out, because the former WWE wrestler wasn't happy with Diesel's producing decisions. It also cited anonymous "production sources" who said Johnson and other members of the crew were upset that Diesel regularly arrived late to shoot scenes, spending time in his trailer instead. TMZ's sources also said Diesel was arrogant, and criticized his co-stars' acting.

Last week, Diesel was asked about the disagreement with Johnson, and avoided going into specifics.

"I don't think the world really realizes how close we are, in a weird way," Diesel told USA Today. "I think some things may be blown out of proportion. I don't think that was his intention. I know he appreciates how much I work this franchise. In my house, he's Uncle Dwayne."